#include <iostream>
#include <string>
using namespace std;

class A{
    mutable int a;
    public:
        A(){
            cout << "A's Constructor called \n"; 
        }
        ~A(){
            cout << "A's Destructor called \n";
        }
};

class B{
    A a;
    public:
        B(){
            cout << "B's Constructor called \n";
        }
        ~B(){
            cout << "B's Destructor called \n";
        }
};

int main(){
    B b1;
}
